The present invention relates generally to a multichamber device; and more particularly to a device having a plurality of microchambers particularly suitable for biological, biochemical, chemical, genetic, microscopic, or spectroscopic analyses.
Genomics, proteomics, and drug discovery are generating a need for expanded versatility of applications for high-throughput screening (e.g., assays performed in large number). Advances in combinatorial chemistry and genomics have resulted in the generation of large libraries of novel compounds. Additionally, combining combinatorial chemistry (novel compounds to be screened) with genomics (expressing potential drug targets in living cells) has put high-throughput screening of live cells in demand. For example, in developing and testing biological substances (e.g., including, but not limited to, genetic vectors, genetic sequences, vaccines, drugs, growth factors, cytokines, chemicals, enzymes, and the like), it may often be desirable to assay for the response of live cells after treatment with a biological substance; and additionally to assay for the responses in high-throughput screening, wherein a cell response may be in a morphological, physiological, biological, or biochemical manner.
The development of automated or semi-automated techniques and instruments currently use microtiter plates with a plurality of wells for assays. However, traditional microtiter plates have several disadvantages. First, in assaying live, adherent cells cultured at the bottom of a well, assay reagents pipetted directly down on the cells may disrupt or otherwise disturb the cells. It is known in the art that some cell monolayers will detach completely from the bottom of a well in response to disruption due to contact with a direct injection of reagent from a pipette. Secondly, since the lid must be removed from a microtiter plate to add reagents, all wells are exposed simultaneously. Reagents pipetted directly down into the exposed wells can splash causing cross-contamination between the exposed wells, as well as causing variance in the reproducibility of results. Additionally, evaporation frequently occurs in conventional microtiter plates leading to variations in fluid volumes between wells. Most of the evaporative loss occurs when removing a microtiter plate from an incubator, and when the lid is removed to add reagents. Also, cultured cells are very dependent upon supplying them with sufficient oxygen for respiration. However, in conventional microtiter plates, the supply of oxygen for cell respiration is from the header space above the cells in each well. Thus, in conventional microtiter plates the volume or surface provided for gas exchange, as relative to the volume or surfaces of the whole container, is either inefficiently used and/or results in limiting the rate of gas exchange or of equilibration of gases. This is even more evident for cells cultured in microtiter wells in which rate of cell growth, cell densities, and total cell numbers, are frequently low due to space, surface area, and gas exchange limitations.
Thus, there is a need for methods and devices capable of performing automated analyses of live cells in high-throughput screening.
It is a primary object of the present invention to provide a device having one or more microchambers, wherein to introduce a fluid into each microchamber does not require direct access to the microchamber.
It is another object of the present invention to provide a device having one or more microchambers, wherein each microchamber is a closed, vented environment.
It is another object of the present invention to provide a device having one or more microchambers, wherein the device has at least one liquid impermeable, gas permeable membrane in a liquid-tight seal with each microchamber in providing for uniform gas exchange and gas equilibrium available to cells in the microchamber.
It is yet another object of the present invention to provide a device having one or more microchambers, wherein introducing a fluid into each microchamber does not require direct access to the microchamber, wherein each microchamber is a closed, vented environment, and wherein the device has at least one liquid impermeable, gas permeable membrane in a liquid-tight seal with each microchamber in providing for uniform gas exchange and gas equilibrium available to cells in the microchamber, and for preventing the escape of fluid from the microchamber.
It is a further object of the present invention to provide a method for introducing a fluid into the device according to the present invention such as useful in assaying of analyte using the device.
Briefly, the invention provides for a device comprising at least one microchamber, and more preferably a plurality of microchambers. In a preferred embodiment, the device comprises a planar base comprising a plurality of apertures therethrough, wherein the planar base is sandwiched between 2 liquid impermeable membranes, and wherein at least one of the membranes is gas permeable. The membranes are each sealed to the respective surface of the base in a manner that forms a liquid-tight seal around each aperture of the base. Thus, a sheet of membrane is used to individually seal around each aperture, and thereby avoids the need to cut, and the complexity to seal, small membrane pieces and then attach each piece individually for sealing around each aperture. Spatially arranged in the base of the device is one or more sets of apertures, wherein the apertures comprising a set are in operative communication, and wherein a set of apertures comprises: a microchamber with a fluid flow groove; a vent aperture; and a filling port. Preferably, a set of apertures has its own microfluidics in confining a fluid to the set; i.e., each microchamber is in fluid flow communication with its own individual filling port via a fluid flow groove therebetween. To use the device, and for each set of apertures of the base, a fluid is introduced into the filling port. Typically, a pipetting device is used to deliver the fluid, wherein a tip of a pipette is inserted into the filling port, and the fluid is delivered under positive pressure. One or more forces selected from the group consisting of positive pressure associated with pipetting, gravity, capillary force, and a combination thereof, moves the fluid down through the filling port and along fluid flow groove so that the fluid enters into the microchamber in fluid flow communication therewith. As the fluid level rises in the microchamber, air that is in the microchamber (prior to entry by the fluid) is displaced out of the microchamber, through the vent aperture and out one or more vent holes in causing the air to be vented to the exterior of the device. The device may further comprise one or more septums, with a septum being inserted into the desired aperture or apertures of the device. The device may also comprise one or more lids securable to the base of the device, wherein the one or more lids covers a surface of the base selected from the group consisting of a top surface, a bottom surface, and a combination thereof (e.g., a first lid covering the top surface and a second lid covering the bottom surface). Thus, the device according to the present invention provides: (a) a plurality microchambers, each microchamber having a closed, vented environment; (b) at least one gas permeable membrane for a more uniform gas exchange and gas equilibrium, available to cells or other analyte contained within the microchamber, than that provided by the header space in a standard microtiter plate; and (c) a means by which a fluid may be introduced into a microchamber without requiring direct access to the microchamber (e.g., rather than pipetting a fluid directly into the microchamber and directly onto the analyte, the fluid is dispensed into a filling port and the fluid then flows along a fluid flow groove and into the microchamber from the bottom of the microchamber in perfusing (permeating) analyte contained within the chamber comprising the microchamber). Further, provided is a method for introducing a fluid into the device according to the present invention.
The above and other objects, features, and advantages of the present invention will be apparent in the following Detailed Description of the Invention when read in conjunction with the accompanying drawings in which reference numerals denote the same or similar parts throughout the several illustrated views and embodiments.